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Toxicity to microorganisms

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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
October - November 1996
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP-guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Version / remarks:
, corresponds for the most part
GLP compliance:
yes
Test material information:
Composition 1
Analytical monitoring:
not specified
Vehicle:
no
Details on test solutions:
Test concentration of activated sludge: 800 mg/L
Test organisms (species):
activated sludge
Details on inoculum:
- Origin: laboratory scale sewage treatment plant unit which runs predominantly with domestic sewage (South Wupper area water authority)
- Pretreatment: none
Test type:
not specified
Water media type:
not specified
Limit test:
no
Total exposure duration:
5 min
Hardness:
no data reported.
Test temperature:
20 ± 2°C
pH:
ca. 7.7, see tables below.
Dissolved oxygen:
see tables below.
Nominal and measured concentrations:
- Nominal test concentrations (mg/l): 1000, 1800, 3200, 5600, 10 000
- Test substance concentration in physico-chemical oxygen consumption control (mg/l): 10 000
- Test concentration of the activated sludge (mg/l): 800
Details on test conditions:
- Incubation time: 30 min with permanent aeration
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol
Duration:
5 min
Dose descriptor:
EC50
Effect conc.:
5 850 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
The EC values are determined by statistical methods (probit analysis). Test concentration and reference substance concentration result from the quantities used in the preparation and have not been confirmed by analytical methods.
Results with reference substance (positive control):
EC 50 = 15 mg/l
(valid result since the EC50 of the test substance have to be in the range of 5 to 30 mg/l.)
Reported statistics and error estimates:
No details available.

Test substance:

Test
concentration
(mg/l)
respiratory rate
test substance
(mg/l.h)
Phys. Chem.
O2-consumption
(mg/l.h)
Respiratory rate
- phys. chem.
O2-consumption
(mg/l.h)
Inhibition

(%)
1 000 20.4 0.0* 20.4 20.9
1 800 19.0 0.0* 19.0 26.4
3 200 16.8 0.0* 16.8 34.9
5 600 13.2 0.0* 13.2 48.8
10 000 9.6 0.0 9.6 62.8
Control, mean 25.8    
Control 1 25.2
Control 2 26.4

* The physico chemical oxygen consumption is determined at 10 000 mg/l test substance.

No physico chemical oxygen consumtion has been determined. Therefore lower concentrations of the test substance cause no physico chemical oxygen consumption (deduced values).

Reference substance:

Test concentration
(mg/l)
respiratory rate
(mg/l.h)
Inhibition
(%)
2.5 21.6 16.3
5 19.5 24.4
10 15.6 39.5
20 11.0 57.4
40 7.2 72.1
Validity criteria fulfilled:
yes
Remarks:
All validity criteria of the test method were met.
Conclusions:
The study is regarded as a valid guideline study with GLP compliance. The toxicity of the test item to activated sludge gave the result EC50 = 5850 mg/l.
Executive summary:

The acute toxicity to microorganisms of (benzylamine)trifluoroborn was tested according to EU Method C.11. The method assessed the effect of the test item by measuring the respiration rate under defined conditions in the presence of different test concentrations. The study was conducted under GLP compliance. A mixed population of aquatic microorganisms (activated sludge), taken from a laboratory scale sewage treatment plant unit which runs predominantly with domestic sewage (South Wupper area water authority) was used as inoculum. An incubation period of 30 min was chosen with aeration. Two controls without test item were included in the test design. The sensitivity of the activated sludge was checked using 3.5 -Dichlorophenol as reference compound. The physico-chemical oxygen consumption control was carried out, since some substances may consume oxygen by chemical reactivity. Direct weighings were prepared to give the different test item concentrations, which were 1000, 1800, 3200, 5600 and 10000 mg/L. 3.5 -Dichlorophenol was used in the concentrations of 2.5, 5, 10, 20 and 40 mg/L. 10000 mg/L test item was included in the physico-chemical oxygen consumption control. No analytical methods were applied.

Analysis of the respiration rates at the end of the test gave the following result: EC50 = 5850 mg/L. The EC50 value of the reference compound was measured to be 15 mg/L, thus being in the validity range of 5 - 30 mg/L.

Description of key information

EU Method C.11, GLP, activated sludge from a sewage treatment plant running with domestic sewage
EC50 = 5850 mg/L
EC10 = 463 mg/L

Key value for chemical safety assessment

EC50 or LC50 for microorganisms:
5 850 mg/L
EC10, LC10 or NOEC for microorganisms:
463 mg/L

Additional information

The acute toxicity to microorganisms of (benzylamine)trifluoroborn was tested according to EU Method C.11. The method assessed the effect of the test item by measuring the respiration rate under defined conditions in the presence of different test concentrations. The study was conducted under GLP compliance. A mixed population of aquatic microorganisms (activated sludge), taken from a laboratory scale sewage treatment plant unit which runs predominantly with domestic sewage (South Wupper area water authority) was used as inoculum. An incubation period of 30 min was chosen with aeration. Two controls without test item were included in the test design. The sensitivity of the activated sludge was checked using 3.5 -Dichlorophenol as reference compound. The physico-chemical oxygen consumption control was carried out, since some substances may consume oxygen by chemical reactivity. Direct weighings were prepared to give the different test item concentrations, which were 1000, 1800, 3200, 5600 and 10000 mg/L. 3.5 -Dichlorophenol was used in the concentrations of 2.5, 5, 10, 20 and 40 mg/L. 10000 mg/L test item was included in the physico-chemical oxygen consumption control. No analytical methods were applied.

Analysis of the respiration rates at the end of the test gave the following result: EC50 = 5850 mg/L. The EC50 value of the reference compound was measured to be 15 mg/L, thus being in the validity range of 5 - 30 mg/L.